Production of 1,5-cyclo-octadiene from butadiene



United States Patent 3,219,714 PRODUCTION OF 1,5-CYCLO-0CTADIENE FROM BUTADIENE Nikolaus von Kutepow, Karisruhe-Rueppnrr, and Huberi'us Seibt and Fritz Meier, Ludwigshafen (Rhine), Gartenstadt, Germany, assignors to Badische Anilin- & Soda-Fahrik Aktiengesellschaft No Drawing. Filed July 3, 1961, Ser. No. 121,362 Claims priority, application Germany, July 7, 1960, B 58,507 8 Claims. (Cl. 260-666) This invention relates to the production of cyclo-olefines, especially 1,5-cyclo-octadiene.

It is known to dimerize 1,3-butadiene, hereinafter referred to briefly as butadiene, by thermal non-catalytic methods to 1,5-cyclo-octadiene and 4-vinylcyclohexene- (1). Only a small proportion of 1,5-cyclo-octadiene is thus obtained. An increase in this proportion is achieved by the use of nickel-containing catalysts at temperatures between 90 and 150 C. and at increased pressure in the presence or absence of solvents. Thus, nickel cyanide and complex nickel compounds have been used as catalysts, for example nickel carbonyls in which at least one carbonyl group has been replaced by an organic phosphite. However, a yield of only 23% of the theory of 1,5-cyclo-octadiene is achieved in this way. A further increase in the yield may be achieved according to another known method by activating the nickel compound before or during dimerization by treatment with acetylene. Coemployment of acetylene however is troublesome. Moreover, under these conditions high molecular weight products form and also reaction products of acetylene which can be separated only with difiiculty from the 1,5-cyclo-octadiene formed.

Addition of other activators, such as cyclopentadiene or dicyclopentadiene, has been proposed to shorten the reaction period. Even with these catalysts, however, the maximum yield of cyclo-octadiene obtainable is only 75.5%.

In reactions of this kind it is usual to characterize the results by the conversion, the selectivity and the yield. These terms are defined as follows:

Weight of diolefine reacted weight of product obtained selecnvlty weight of diolefine reacted conversion selectivity Yield weight of product obtained weight of diolefine supplied X100 It is an object of this invention to prepare 1,5-cyclooctadiene with high selectivity.

It is another object of this invention to prepare 1,5- cyclo-octadiene with a high yield.

It is a further object of this invention to prepare new catalysts which are suitable for the dimerization of butadiene to 1,5-cyclo-octadiene.

Other objects and advantages of the invention will become apparent to the expert from the following description.

The said objects and advantages are achieved by dimerizing butadiene at a temperature of at least 50 C. in the presence of a phosphite-containing nickel complex with less than four ligands which has been obtained by reaction of an organic nickel complex compound containing O-valent nickel and being free from carbon monoxide with an ester of phosphorus acid.

Ice

For the production of the phosphite-containing nickel complexes to be used according to this invention, nickel complex compounds are used which contain no carbon monoxide and in which the nickel is O-valent. Complexes of this kind are nickel(0) complexes with e s-unsaturated aldehydes and with one-unsaturated nitriles. Nickel(0) complexes of the lower aliphatic a,;8-unsaturated aldehydes, i.e., aldehydes with three to six carbon atoms, for example acrolein and y-bromocrotonaldehyde, of the lower aliphatic a,/5-unsaturated nitriles with three to six carbon atoms, such as acrylonitrile and crotonyl nitrile, and also cinnamyl nitrile, are especially suitable. Examples of complexes of this kind are: nickel(0)-bis-acrolein, nickel(0)- bis acrylonitrile, nickel(0)-biscinnamonitrile and nickel O) -bis-fumaronitrile.

The common feature of these nickel complexes is that the ligands are combined by means of the 1r-electrons contained in the olefinic double linkages. In general, the readily accessible nickel-bis-acrylonitrile is preferred.

As esters of phosphorous acid there are used those of aliphatic alcohols, especially those with branched chains, for example a-lkanols with 1 to 12 carbon atoms, but mainly of aromatic hydr-oxy compounds, such as phenols and naphthols. The phenols and naphthols may be substituted by alkyl radicals, aryl radicals, halogen atoms or alkoxy groups, for example by one to three alkyl radicals with 1 to 12 carbon atoms or by phenyl radicals. It is especially advantageous to use phenyl esters of phosphorous acid in which substituents are present in o-position to the phenolic hydroxy group. Compounds which contain voluminous substituents in o-position are especially active. Examples of substituents are methyl, ethyl, propyl, isopropyl, hutyl, isobutyl, tertiary-butyl, cyclohexyl and phenyl radicals.

Examples of phosphites which may be used are: trimethyl phosphite, triethyl phosphite, tri-isopropyl phos-, phite, tri-iso-butyl phosphite, tri-(Z-ethylhexyl) phosphite, tridodecyl phosphite, triphenyl phosphite, tri-o-cresyl phosphi-te, -tri-m-cresyl phosphite, tri-p-cresyl phosphite, tri-(2, 4-dimethylphenyl) phosphite, tri-o-isopropylphenyl phosphite, tri-(2,6di-methylphenyl) phosphite, tri-p-iso-butylpheny-l phosphite, tri-p-isooctylphenyl phosphite, tri-(Z- isopropyl-S-methylphenyl) phosphite *tri-thymylphosphite), tri-carvacryl phosphite, tri-(2,4-diisopropylphenyl) phosphite, tri-odiphenyl phosphite, tri-(o-methoxyphenyl) phosphite, tri-a-naphthyl phosphite, tri-fl-naphthyl phosphite, tri-p-chlor-phenyl phosphite, tr-i-o-chlorphenyl phosphite, and tri-m-chlorphenyl phosphite.

The reaction between the organic nickel complex free from carbon monoxide and the phosphite may be reproduced for example with nickel-bis-acrylonitrile and triphenyl phosphite as follows:

The reaction of these components to form the catalysts to be used according to this invention is effected by mixing the organic nickel(0) complex free from carbon monoxide with the phosphite in about the mol ratio 1:05 to 1:5, preferably in the ratio 1:3 to 1:5, with substantial exclusion of oxygen in a solvent or diluent inert under the reaction conditions at room temperature or at an elevated temperature, i.e., at a temperature between about 20 and about C. By the phrase with substantial exclusion of oxygen we mean that the oxygen content in the gas space above the liquid reaction mixture in the reaction vessel should not exceed about 3 vol. percent. If larger amounts of oxygen are present, substantial amounts of nickel(0) complex will be decomposed. Usually, this reaction is carried out at normal pressure but it may also be carried out under increased or reduced pressure. Suitable solvents are aliphatic, cycloaliphatic and aromatic hydrocarbons, ethers and nitriles of lower fatty acids, especially those whose boiling point at the pressure chosen lies in the temperature range of 20 to 120 C. This means that usually solvents boiling between 20 and 120 C. at normal pressure are used, for example hexane, the various octanes, gasoline fractions of this boiling range, cyclohexane, benzene, toluene, but solvents of lower boiling point may be used when the reaction is carried out under pressure, or of higher boiling point when the reaction is carried out, often with advantage, under reduced pressure. Xylene, tetrahyd'ronaphthalene, decahydronaphthalene and liquid butane or propane may therefore also be used.

It is also possible however to use open-chain or cyclic ethers, for example diethyl ether, di-isopropyl ether, diisobutyl ether, dioxane or tetrahydrofurane. Of the nitriles, the most suitable are those with two to five carbon atoms, for example acetonitrile and pro-pionitrile.

The ratio of the reactants (nickel complex and phosphite) to the solvent or diluent may vary within wide limits; it is possible to use saturated solutions in which the organic nickel complex is suspended, but very dilute solutions may also be used although it is not convenient to work in a greater dilution than 1 part of nickel complex to 10 parts of solvent. The progress of the reaction can readily be recognized by the change in color of the reaction mixture. The nickel complex solution or suspension is as a rule red in color. It changes its color toward yellow or becomes colorless, and at the same time the phosphite-containing nickel complex may be precipitated in solid form. In general the reaction is ended after 1 to 2 hours. If the complex is precipitated in insoluble form, it is filtered off by suction, washed with an organic solvent and dried. If it remains in solution, this solution mayeit her be used directly for the dimerization or the solvent can be distilled off and the residue used for the dimerization. In some cases it may be convenient to precipitate the complex formed by adding lower alcohols, for example methanol, ethanol or propanol. All operations are preferably carried out while excluding oxygen. In many cases definite new compounds are obtained, for example of the composition wherein R represents a member selected from the group consisting of alkyl, aryl, alkylaryl and halogenaryl,

Z represents a member of the group consisting of 3- ethylenically unsaturated aldehydes and nitriles,

x stands for an integer of from 2 to 3, y stands for an integer of from 1 to 2,

the sum of x and y-l being an integer of from 2 to 3.

In the preferred complexes, those phosphites and the above-mentioned a,fi-ethylenically unsaturated compounds are used which above were called especially advantageous.

Thus

tris- (triphenyl-phosphite) -nickel,

bis-(tri-o-Ctesybphosphite) -acrylonitrile-nickel,

tristri-m-tolylphosphite -nickel,

bis-( 3, 5 -dimethylphenyl-phosphite) -mono-acrylonitrilenickel,

bis- (tri-thymyl-phospite) -nickel,

bi-s- (tri-o-diphenyl-phosphite -nickel,

bis- (tri-2,4-ditertiary-butylphenyl-phosphite) -nickel,

bis- (tri-4-tertiary-butylphenyl-lphosphite -nickel,

tris- (tri-o-chlorphenyl-phosphite) -nickel and bis- (tri-4 iso-octylphenyl-phosphite -nickel are obtained in this way.

In other cases mixtures of compounds are obtained in which it must be assumed, on the basis of analysis, that compounds in which the nickel is enclosed by two ligands and compounds in which the nickel is enclosed by three ligands are present side by side.

The phosphite-containing nickel(0) complexes are yellowish white crystalline compounds.

It is obvious that either individual complex compounds of the said kind or mixtures of different complex compounds of the said kind may be used.

Dimerization of butadiene with the catalysts of the kind described above is effected under the conditions known for this reaction. The catalyst is used in a concentration of about 0.5 to about 5%, preferably 2 to 4% by weight with reference to butadiene. In some cases, however, lower concentrations, for example 0.1% by weight, are sufficient.

It is usual to coemploy inert solvents or diluents although this is not necessary because liquid butadiene also acts as a solvent. It is also possible to use saturated and unsaturated aliphatic, cycloaliphatic or aromatic hydrocarbons, especially those with a boiling range between and 250 C., such as n-hexane, noctane, gasoline fractions, benzene, toluene, xylenes, p-cymene, cyclohexane, cyclo-octane, cyclo-octadiene alone or in admixture with other solvents, tetrahydronaphthalene, decahydronaphthalene, dicyclopentadiene, and also liquid carboxylic acid amides, such as dimethylformamide, N,N-di-methylacetamide, N-butylpyrrolidone, cyclic ethers, such as dioxane or tetrahydrofurane, nitriles, such as acetonitrile or propionitrile, or ketones, such as acetone or cyclohexanone. Naturally, mixtures of the said solvents may also be used. The yield, varies according to the solvents used, but the choice of solvent is not a feature of the invention.

In some cases it is convenient to add a polymerization inhibitor to prevent polymerization of the butadiene. Such inhibitors are known; examples are mononuclear or polynuclear monophenols or polyphenols, such as phenol, pyrocatechol, p-tertiary-butylpyrocatechol, resorcinol, 2,4-dimethyl-6-tertiary butyl phenol, hydroquinone, quinones, phloroglucine, pyrogallol and also amines, espe cially N,N'-di-isopropyl p-phenylene-diamine and phe nothiazine. These inhibitors are used in amounts of 0.01 to 3% by weight with reference to the diolefine.

Dimerization may be carried out within a wide temperature range above at least 50 C., for example in the range of 50 to 250 C. It is preferred to work between about and 150 C.

Dimerization is in general carried out at the pressure determined by the vapor pressure of butadiene, of any solvent used and of the cyclo-octadiene formed, for example in the range of 3 to 20 atmospheres. It is also possible to work at higher pressures by forcing in inert gases, such as nitrogen, rare gases, saturated hydrocarbons, gaseous hydrocarbons containing a single olefinic unsaturation, or carbon dioxide. In principle, however, the process may be carried out at normal pressure, for example by blowing butadiene in gaseous form into a solution of the catalyst in any of the said solvents.

The butadiene may be used pure or in admixture with other saturated or unsaturated hydrocarbons, for example as obtained in the cracking of higher hydrocarbons.

The process may be carried out batchwise, semiconti-nw ou-sly or fully continuously.

In batchwise operation, the catalyst may for exam ple be placed, preferably while excluding oxygen, in a diluent or solvent in an autoclave and liquid butadiene added. The relative proportions of catalyst and butadiene may be varied within wide limits. For example 0.5 to 5 preferably 2 to 4%, by weight of catalyst with reference to butadiene may be used. The autoclave is then heated to the reaction temperature, for example to to 120 C., a pressure of 3 to 20 atmospheres gage being set up depending on the diluent used. The reaction period up to practically complete conversion is in general about 12 to 48 hours. If however incomplete conversion is acceptable, the reaction may be discontinued after only 1 to 2 hours because the bulk, i.e., about 80 to of the maximum amount is converted Within this time. The conversion naturally depends on the activity of the, catalyst and with some catalysts a satisfactory degree of conversion can be reached after only 10 to, 2 minutes.

After cooling, 9. reaction product is obtained which is liquid at room temperature and which, if desired after filtration, is fractionally distilled. The main fraction passing over is 1,5-cyclo-octadiene. Small amounts of 4-vinyl-cyclohexene-(l) are obtained as byproduct and small amounts of higher polymers as distillation residue.

The process may also be carried out continuously, for example by the so-called trickling method or by introducing the gaseous reactants into the liquid phase. Butadiene may for example be injected into a catalyst solution kept at the reaction temperature and the pressure set up at this temperature, or butadiene with the catalyst in the propor tions specified for the discontinuous method, and if desired also the solvent, may be led at the reaction temperature and under pressure set up at this temperature over large-surfaced shaped packing. Residence periods of 10 to 20 minutes are usually sutficient, especially if the butadiene set free by the subsequent expansion is returned in circulation.

1,5-cyclo-octadiene is obtained by the present process in at least as good a yield as in the known methods which are carried out in the presence of acetylene. In some cases, the yields are appreciably higher than in the known methods. It is not necessary to use glass-lined autoclaves and carefully to exclude moisture, so that the new process is far better suited to large-scale industrial operation than the known methods. The favorable ratio of 1,5-cyclooctadiene to 4-vinyl-cyclohexene-(1) is also of advantage.

The reaction products are valuable chemical intermediates, for example for the production of cyclo-octane and cyclo-octene which are important for the production of valuable polymers.

The invention is illustrated by, but not limited to, the following examples.

Example 1 For the preparation of the catalyst, 32.4 grams of nickel-bis-acrylonitrile are introduced while excluding air into a H. three-necked flask provided with a dropping funnel, stirrer and reflux condenser and suspended in about 500 ml. of absolute ether. 200 grams of triphenyl phosphite is added. The mixture is boiled under reflux for 8 hours with vigorous stirring. The initially intense red colored solution is discolored as the reaction proceeds. The product is filtered otf by suction while excluding air and washed with ether. After drying in an oil pump vacuum, 193 grams of a yellowish white finely crystalline substance is obtained which according to analysis has the formula:

s s)3]3 Analysis:

Ni, percent percent percent percent Found 5. 2 Calculated for N i[P (0 0 21 31 116 ml. of liquid butadiene (75.5 grams), 100 ml. of n-hexane (66 grams) and 500 mg. of hydroquinone are placed while excluding air in a H. rotating autoclave of high-grade steel rinsed with nitrogen. 5 grams of the nickel catalyst described above, which is a tris-triphenylphosphite-nickel, is added thereto. The mixture is heated to 120 C. in the autoclave and kept at this temperature for twelve hours, a pressure of about 20 atmospheres gage being set up. After cooling, 132 ml. of a pale green liquid is obtained as reaction product, which is filtered and then fractionally distilled. 31.3 grams of 1,5-cyclooctadiene is obtained besides 5.6 grams of 4-vinyl-cyclohexene-( 1) and 4 grams of a liquid distillation residue. The conversion is accordingly 54%, the selectivity for 1,5-cyclo-octadiene 77% and the yield of cyclo-octadiene 41.5%.

6 Example 2 A mixture of 116 ml. (75.5 grams) of butadiene, ml. (66 grams) of n-hexane, 0.5 gram of hydroquinone and 5 grams of the nickel catalyst used in Example 1 is heated for twelve hours under a nitrogen pressure of 30 atmospheres gage at C. in a H. rotating autoclave of high-grade steel. After cooling, 155 ml. of liquid reaction product is obtained from which 36.5 grams of 1,5- cyclo-octadiene is obtained by fractional distillation over a circulating band column. 7.4 grams of 4-vinylcyclohexene-(l) and 8 grams of high-boiling constituents are isolated as byproducts. The conversion is thus 68.3 the selectivity 71% and the yield 49.5%. Investigation by gas chromatography shows however that a yield of 61% of the theory of 1,5-cyclo-octadiene is achieved.

Example 3 For the preparation of the catalyst, 11.2 grams of nickel-bis-acrylonitrile is introduced under nitrogen free from oxygen and water into a three-necked flask provided with a stirrer, reflux condenser and nitrogen inlet pipe, and suspended in 250 ml. of ether free from oxygen and water. 72 grams of tri-o-tolyl phosphite is then added. The mixture is boiled under reflux for 2 hours. The color of the originally red solution changes to yellow and the sediment passes into solution. The reaction mixture is then cooled for some hours in an ice-bath and the deposited crystals are filtered off by suction while excluding oxygen, washed with ether and dried in vacuo. 50.2 grams of lemon yellow crystals is obtained which upon heating in the air at C. are decomposed and which in the absence of air show discoloration above 120 C.

According to elementary analysis and on the basis of the infra-red spectrum, the following composition is assumed for the compound:

1.5 grams of the catalyst described above, 0.2 gram of hydroquinone and 40 ml. (31.2 grams) of cyclohexane are charged while excluding air into a 250-ml. pressure vessel. Then 36 grams of liquid butadiene is forced in. The pressure vessel is heated to 100 C. for 12 hours with shaking, a pressure of about 10 atmospheres gage being set up. After cooling, the reaction mixture is distilled, the fraction passing over up to 125 C. at 25 mm. Hg being collected. 2.2 grams of residue (catalyst and resin) and 63 grams of distillate are obtained, 30.6 grams of 1,5-cyclo-octadiene and 2.36 grams of 4-vinyl-cyc1ohexene-(l) are detected in the distillate by gas chromatography. By distillative separation through an efiicient column, about 90 to 95% of the 1,5-cyclo-octadiene detected by gas chromatography can be isolated in the pure state (boiling point of the 1,5-cyclo-octadiene to 151 C. at 760 mm. Hg). The conversion therefore lies at 91.5%, the selectivity for 1,5-cyclo-octadiene at 83% and the yield at 76%.

Example 4 1.5 grams of the catalyst described in Example 3, 0.2 gram of hydroquinone and 34.8 grams of decahydronaphthalene are charged into a 250-ml. pressure vessel. 35 grams of liquid butadiene is forced in and then the pressure vessel is heated for five hours at 120 C. while shaking. By working up as in Example 3, 65 grams of distillate and 3.2 grams of residue (catalyst and resin) are obtained. 25.8 grams of 1,5-cyclo-octadiene and 2.5 grams of 4-vinyl-cyclohexene-(1) can be detected in the distillate by gas chromatography. The conversion thus lies at 93.5%, the selectivity for 1,5-cyclo-octadiene at 82.5% and the yield at 77%.

Example 5 For the preparation of the catalyst, 51 grams of nickel()-bis-acrylonitrile and a solution of 293.5 grams of trithymyl phosphite in about 600 ml. of dioxane are introduced into a 14. three necked flask fitted with a stirrer and reflux condenser. While stirring, the temperature is raised to about 70 C., the nickel(0)bis-acrylonitrile, originally in suspension, passing into solution in the course of 1 to 2 hours. The yellow solution obtained is freed from any solid residues present by filtration and concentrated to about 250 ml. under reduced pressure. After cooling, the crystalline yellow substance is filtered off, washed with methanol and dried in a vacuum exsiccator. 274.5 grams of an air-sensitive substance is obtained which according to analysis has the formula CH(CH3)2 NiP-O 18.3 grams of the yellow air-sensitive nickel(0)-bis-trithymyl phosphite complex in about 400 ml, of cyclohexane and 1 gram of hydroquinone as stabilizer is charged into a 2-1. agitated autoclave after it has been flushed with nitrogen. The autoclave is then heated to 80 C. Gaseous butadiene is led into the autoclave from a steel flask attached thereto through a reducing valve. The butadiene take-up is checked by weighing the steel flask. About 600 grams of butadiene is taken up by the reaction mixture in the course of eight hours. Then the reaction product obtained in the autoclave (952 grams) is distilled at a pressure of 25 mm. Hg and a bottoms temperature up to 100 C. 16.7 grams of resin remains. The distillate obtained is fractionated at normal pressure in a column packed with Raschig rings. The fraction passing over between 80 and 131 C. contains, besides solvent, 7.0 grams of 4-vinyl-cyclo-hexene-(1), the fraction passing over from 131 to 149 C. (about 28 grams) consists of about equal parts of 4-vinyl-cyclohexene-(1) (13.77 grams) and 1,5-cyclo-octadiene (14.3 grams). Then 431.3 grams of pure 1,5-cyclo-octadiene passes over between 149 and 151 C. Upon further heating, a distillate is obtained which contains 12.5 grams of 1,5-cyclo-octadiene and 10.8 grams of constituents of higher boiling point. Accordingly, there are obtained in all 458.1 grams of 1,5-cyclo-octadiene, 20.7 grams of 4-vinyl-cyclohexene-(1) and 27.5 grams of resin and high-boiling constituents. Referred to the butadiene reacted, the yield of 1,5-cyclo-octadiene is 90.5 and of 4-vinylcycloheXene-(1) 4.1%. The conversion lies at 84%, the selectivity for 1,5-cyclooctadiene at 90.5% and the yield at 76%.

Example 6 For the preparation of the catalyst, 13.7 grams of nickel (0)-bis-acrylonitrile is caused to react with exclusion of air with a solution of 89.7 grams of tri-o-diphenyl phosphite in about 250 ml. of tetrahydrofurane in a 500-ml. three-necked flask fitted with a stirrer and reflux condenser. After stirring for about two hours at a temperature of 60 C., the nickel compound has practically completely passed into solution with a yellow color. Small amounts of residue are filtered off, the solvent is withdrawn under reduced pressure, the oily residue taken up with ether, filtered again and the ether evaporated. 90.3 grams of a foam which solidifies to form a yellow powder of low bulk density is obtained; according to analysis it has the composition:

40 ml. (35 grams) of benzene and 1.0 gram of the above-described nickel(0) complex are charged into a 250 ml. shaking bomb which has been flushed with nitrogen. About 30 grams of butadiene is then forced into the solution and the reaction vessel heated at C. for twelve hours. According to the pressure drop, the reaction is substantially ended after only 30 to 60 minutes. 72.5 ml. of reaction mixture is obtained from the bomb. In the distillation, 57 grams of a colorless liquid passes over and 1.8 grams remains as residue, of which 1.0 gram is catalyst and 0.8 gram resin. The distillate contains, as may be ascertained by gas chromatography, 25.7 grams of 1,5-cyclo-octadiene and 1.4 grams of 4- vinyl-cyclohexcne-(l); the total yield, with reference to butadiene reacted, is 92% of 1,5-cyclo-octadiene, 5% of 4-vinyl-cyclohexene-(1) and 3% of resin; the mole ratio of 1,5-cyclo-octadiene to 4-vinyl-cyclohexene-(l) is 18.3:1. The conversion thus is 93%, the selectivity for 1,5-cyclo-octadiene 92% and the yield 86%.

Example 7 For the preparation of the catalyst, 2.6 grams of nickel(0)bis-acrylonitrile and 20.4 grams of tri-(2,4-ditertiary-butyl-phenyl) phosphite are reacted in about 150 150 ml. of dioxane while stirring at 60 to 70 C. The reaction is ended after one to two hours. A dark-colored solution is obtained. It is filtered, the solvent distilled off under reduced pressure and the oily residue obtained is taken up with ether. After filtering off the ether, 17.5 grams of a yellow-brown compound remains which according to analysis has the formula:

2.5 grams 'of this complex compound is reacted as described in Example 6 in a shaking autoclave with about 30 grams of butadiene and 40 ml. of cyclohexane at C. 59.8 grams of a dark-colored reaction mixture is obtained. By distillation of this mixture, 56.6 grams of a colorless distillate is obtained which, according to gas chromatography, contains 25 grams of 1,5-cyclo-octadiene and 1.3 grams of 4-vinyl-cyclohexene-(1). The residue (3 grams) contains 0.5 gram of resin and high boiling products in addition to the catalyst used. The conversion is 89.5%, the selectivity for 1,5-cyclo-octadiene 93% and the yield 83.5%.

Example 8 A ready-made solution of the camplex Ni (CH =CHCN) [P (OC H CH -ortho z is prepared in a H. agitated autoclave from a mixture of 3.2 grams of nickel(0)bis-acrylonitrile, 13.6 grams of tri-o-tolyl phosphite and 133.8 grams of 1,5-cyclo-octadiene, by stirring the components for two hours at 70 C. under an argon atmosphere. Into this catalyst solution, 300 grams of a liquid mixture of butene and butadiene (containing 134 grams of 1,3-butadiene) is pressed. The autoclave is then heated at 100 C. for three hours while stirring, a pressure of 20 atmospheres gage being set up. After cooling, the autoclave is decompressed, the eflluent gases being led through a trap cooled to 78 C. The reaction mixture obtained (318 grams) gives 250.4 grams of colorless distillate by distillation at 18 mm. Hg in the range of 30 to C. In the cooled trap, 47.5 grams of condensate is obtained which consists mainly of butene. 19.8 grams of black oil remains in the flask as distillation residue. By gas chromatographic analysis of the distillate, a content of 90.5% of 1,5-cyclo-ctadiene and 3.73% of 4-vinyl-cyclohexene- (l) is determined. After deduction of the 1,5-cyclooctadiene used as solvent, 114.7 grams of 1,5-cyclo-octadiene and 9.4 grams of 4-vinyl-cyclohexene-(l) are formed as well as 3.0 grams of resin. The butadiene conversion is 94.8%.

1,5-Cyc1o- 4-Vinyl- Resin, octadiene, cyclohexenepercent percent (1), percent Selectivity 90. 3 7. 4 2. 4 Yield 85. 6 7. U 2. 2

Example 9 Ni (0C6H4CH3)3]3 Analysis:

Percent Percent Percent Percent Percent C N Ni P N Found 67. 9 5. 6 4. 0 7. 2 0. Calculated 67. 81 5. 69 5. 2 8. 33

1.5 grams of tris-(tri-rn-tolyl-phosphite)-nickel, 0.2 gram of hydroquinone and 40 ml. of cyclohexane are charged into a 250-ml. shaking autoclave. Then 27 grams of liquid butadiene is forced in. The autoclave is heated for 12 hours at 120 C. while shaking. As the reaction mixture, 56 grams of a dark brown solution is obtained whch is distilled at 20 mm. Hg and a bottoms temperature up to 100 C. 4.0 grams remains in the fiask as a residue while 48.6 grams of a colorless liquid passes over as a distillate. According to gas chromatographic analysis, this contains 21.2% of 1,5-cyclo-octadiene and 9.2% of 4-vinyl-cyclohexene-(1). Accordingly, 10.8 grams of 1,5-cyclo-octadiene and 4.7 grams of 4-vinylcyclohexene-(l) have been formed. The selectivity is 60% for 1,5-cyclo-octadiene, the yield of 1,5-cyc1o-octadiene is 40.0%

Example 10 1.5 grams of bis-(tri-o-tolyl-phosphite)-nickel-monoacrylonitrile, 0.2 gram of anthraquinone and 57 grams of liquid butadiene are heated for twelve hours at 80 C. in a shaking autoclave of 250 ml. capacity. 50 grams of a red-brown liquid are obtained as reaction mixture. By distillation of this liquid, 43.3 grams of distillate are obtained which according to gas chromatographic analysis contains 87% of 1,5-cyclo-octadiene and 8.9% of 4-viny1- cyclohexene-(l). 4.5 grams of a brown oil remain as distillation residue. Accordingly 37.8 grams of 1,5-cyclooctadiene, 3.9 grams of 4-vinyl-cyclohexene-(1) and 2.8 grams of resin have been formed. The butadiene conversion is 78%, the selectivity in respect of 1,5-cyclooctadiene is 85% and the yield of 1,5-cyclo-octadiene is 66%.

Example 11 5.8 grams of the air-sensitive yellow complex bis-(trio-tolyl-phosphite -nickel-monoacrylonitrile {Ni (CH CHCN) {P (OC H CH -ortho is dissolved in 200 ml. of cyclohexane in a 1-l. threenecked flask. Gaseous butadiene is led under a gage pressure of about 150 mm. Hg at about 70 C. into the solution stirred by an impeller. The originally yellow solution turns red-brown. After leading in butadiene for about four hours, the solution is distilled at 15 mm. Hg and a bottoms temperature of 100 C. 141 grams of a colorless solution is obtained as distillate. According to gas chromatographic analysis this contains 32.6% of 1,5-cyclo-octadiene and 3.5% of 4-vinyl-cyclohexene-(1). Accordingly, 5.0 grams of 4-vinyl-cyclohexene-(1) is formed besides 45.9 grams of 1,5-cyclo-octadiene.

Example 12 9.0 grams of nickel(0)-bis-acrylonitrile is mixed with a solution of 50.6 grams of tri- (a-naphthyD-phosphite in 200 ml. of dioxane while excluding air and then stirred at 60 to C. for 2% hours, the nickel(0)acrylonitrile slowly passing into solution. The solution is filtered under nitrogen as protective gas. The solvent is distilled off from the filtrate under reduced pressure and the oily residue is dissolved in 150 ml. of ether, the solution filtered and the solvent again distilled off. Taking up in ether, filtration and distilling off the ether are repeated twice. 33 grams of a brownish-yellow air-sensitive substance is then obtained as residue; acrylonitrile is not detectable therein and according to analysis it has a mole ratio of nickel to tri(a-naphthyl)-phosphite of 1:2.4.

2.5 grams of the reaction product of nickel(0)-bisacrylonitrile and tri-(oi-naphthyDphosphite, dissolved in 30 ml. of hexane, and 0.1 gram of hydroquinone are charged into a 250 ml. shaking autoclave filled with nitrogen. Then 28 grams of butadiene is forced in and the reaction vessel heated to C., the pressure rising to about 6 atmospheres gage. After heating for twelve hours, the reaction mixture is allowed to cool and distilled at 25 mm. Hg, the still being heated to 100 C. 4.6 grams of residue is obtained which, besides the catalyst and stabilizer, contains 2.0 grams of high boiling hydrocarbons. The distillate (46.5 grams), as shown by gas chromatographic analysis, contains, besides the solvent, 17.8 grams of 1,5-cyclo-octadiene and 2.85 grams of 4- vinyl-cyclohexene-(l). The conversion is accordingly 81%, the selectivity in respect of 1,5-cyclo-octadiene 78.6% and the yield 63.6%

Example 13 4.35 grams of nickel(0)-bis-acrylonitrile is mixed with 20.9 grams of tri-(2,4-dimethylphenyl)-phosphite, dissolved in 100 ml. of tetrahydrofurane, at a temperature of 60 to 70 C. while excluding air. After stirring for two hours, the nickel(0)-bis-acrylonitrile has dissolved. The red-brown solution is filtered with exclusion of air and the solvent distilled off at 25 mm. Hg. A brown viscous residue (21.5 grams) is obtained. This is taken up in about 150 ml. of ether, filtered free from undissolved matter and the solvent distilled ofi. The treatment with ether is repeated twice. A solid residue remains behind.

2.5 grams of this reaction product from nickel(0)-bisacrylonitrile and tri-(2,4-dimethylphenyl)-phosphite, dissolved in 40 ml. of cyclohexane, and 0.1 gram of hydroquinone are placed in a 250-ml. shaking autoclave. 32 grams of butadiene is forced in. The whole is heated to C. and kept for two hours at this temperature. Working up is carried out as described in Example 9, and 0.6 gram of hydrocarbons with a boiling point higher than 100 C. at 25 mm. Hg, 25.7 grams of 1,5-cyclooctadiene and 2.4 grams of 4-vinylcyclohexcne-(1) are obtained. The conversion is 89.7%, the selectivity for 1,5-cyclo-octadiene 89.5% and the yield 80.3%.

Example 14 12.3 grams of nickel(0)-bis-acrylonitrile and 59 grams of tri-(3,5-dimethylphenyl)-phosphite (mole ratio 1:2) are reacted while excluding air at a temperature of 60 to 70 C. with continuous stirring, the nickel(0)-bisacrylonitrile passing completely into solution. The yellow-brown solution is filtered and the solvent competely 1 1 distilled off from the filtrate. The yellow residue is recrystallized from petroleum ether, 31.5 grams of a yellow crystalline compound being obtained which according to analysis is a bis-(tri-3,S-dimethyl(phenyl)-phosphite)-nickel()-monoacrylonitrile By working up the mother liquor, the yield of the complex may be increased.

30 grams of butadiene is forced into a solution of 1.6 grams of the above-described complex compound in 40 ml. of hexane in a 250-ml. shaking bomb and reacted at 100 C. After twelve hours, the reaction mixture is distilled at 25 mm. Hg, the bottoms being heated to 100 C. 4 grams of residue is obtained which besides the catalyst contains 2.4 grams of high boiling hydrocarbons, and 53.2 grams of distillate which according to gas chromatographic analysis contains 18.5 grams of 1,5-cyclo-octadiene and 3.4 grams of 4-vinyl-cyclohexene-(l). The conversion is 81%, the selectivity 76% and the yield of 1,5-cyclo-octadiene 62%.

Example 15 In a manner analogous to that described in Example 14, 11.9 grams of nickel(O)-bis-acrylonitrile is reacted with 68 grams or" tri-(p-tertiary-butylphenyl)-phosphite in 150 ml. of tetrahydrofurane at 60 to 70 C. for about 2 hours while stirring. The yellow solution is filtered, the solvent distilled oil? at 25 mm. Hg, the residue taken up in 150 ml. of ether, this solution filtered and the solvent withdrawn. 72.9 grams of nickel(0)-bis- (p-tertiary-butylphenyl)-phosphite is obtained.

30 grams of butadiene is forced into a solution of 2.5 grams of this complex compound in 40 ml. of hexane in a shaking autoclave filled with nitrogen after the addition of 0.1 gram of hydroquinone. The mixture is heated for twelve hours at 120 C. and the reaction mixture then worked up as described in Example 14. Besides the catalyst, 1.9 grams of high boiling hydrocarbons, 22 grams of 1,5-cyclo-octadiene and 4.4 grams of 4-vinyl-cyclohexene-(l) are obtained. The conversion is accordingly 94%, the selectivity for 1,5-cyclo-octadiene 74% and the yield 70%.

Similar results are obtained when a catalyst is used which has been prepared by reaction of nickel(0)-bisacrylonitrile with tri-(p-iso-octylphenyl)-ph0sphite.

We claim:

1. In a process for the production of 1,5-cyclooctadiene by contacting 1,3-butadiene with a nickel catalyst in the presence of an inert solvent at a temperature between about 50 C. and 250 C., the improvement which comprises using a complex nickel catalyst which has been obtained by mixing in a diluent (A) an ester of phosphorous acid with (B) a complex compound consisting of 0-valent nickel in complex combination with an aliphatic organic compound selected from the group consisting of egg-ethylenically unsaturated aldehydes and a,,8-ethylenically unsaturated nitriles.

2. A process as claimed in claim 1 wherein said organic compound in complex combination with said 0-valent nickel is an u,B-ethylenically unsaturated aldehyde 3. A process as claimed in claim 1 wherein said organic compound in complex combination with said 0- valent nickel is an a,fl-ethylenically unsaturated nitrile.

4. A process as claimed in claim 1 wherein said complex compound (B) is nickel-bis-acrolein.

5. A process as claimed in claim 1 wherein said complex compound (B) is nickel-bis-acrylonitrile.

6. A process as claimed in claim 1 wherein component (A) is the ester of the formula P(OR) wherein R represents a radical selected from the group consisting of alkyl of 1 to 12 carbon atoms, phenyl, naphthyl, and phenyl substituted by at least one substituent selected from the group consisting of alkyl of l to 12 carbon atoms, lower alkoxy, cyclohexyl, phenyl and chloro.

7. A process as claimed in claim 6 wherein component (B) is nickel-bis-acrolein.

8. A process as claimed in claim 6 wherein component (B) is nickel-bis-acrylonitrile.

References Cited by the Examiner OTHER REFERENCES Bigorgne: Comptes Rendus, vol. 250, No. 21, pages 3484-86 relied on, 1960.

Wilke et al.: Angewandte Chemie, page 33 relied on, vol. 73, No. l, 1961.

DELBERT E. GANTZ, Primary Examiner.

TOBIAS E. LEVOW, PAUL M. COUGHLAN, JR., AI-

PHONSO D. SULLIVAN, Examiners. 

1. IN A PROCESS FOR THE PRODUCTION OF 1,5-CYCLOOCTADIENE BY CONTACTING 1,3-BUTADIENE WITH A NICKEL CATALYST IN THE PRESENCE OF AN INERT SOLVENT AT A TEMPERATURE BETWEEN ABOUT 50*C. AND 250*C., THE IMPROVEMENT WHICH COMPRISES USING A COMPLEX NICKEL CATALYST WHICH HAS EEN OBTAINED BY MIXING IN A DILUENT (A) AN ESTER OF PHOSPHOROUS ACID WITH (B) A COMPLEX COMPOUND CONSISTING OF O-VALENT NICKEL IN COMPLEX COMBINATION WITH AN ALIPHATIC ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF A,B-ETHYLENICALLY UNSATURATED ALDEHYDES AND A,B-ETHYLENICALLY UNSATURATED NITRILES. 